Recombinant PilC proteins, methods for producing them and their use

ABSTRACT

The invention relates to recombinant gene sequences for synthesizing a protein having the biological activity of the PilC protein. Furthermore, the invention relates to DNA recombinant methods for the production of proteins having the biological activity of the PilC protein as well as the tools of molecular biology needed therein. Besides, the invention relates to proteins having the biological activity of the PilC protein and its antibodies. Further embodiments of the invention are pharmaceutical compositions with a content of the mentioned proteins or antibodies. Preferably, these pharmaceutical compositions serve as vaccines for the immunization against pathogenic bacteria bearing type 4 pili. The invention also relates to kits for the detection of bacteria bearing type 4 pili or antibodies directed against them containing the mentioned proteins or antibodies. Finally, the invention relates to cellular receptors for bacteria bearing type 4 pili and analogues thereof.

This application claims priority under 35 USC 119 to P 4,336,530.2 Fed. Rep. of Germany, filed Oct. 26, 1993, and PCT/EP94/03494, filed Oct. 25, 1994.

The invention relates to recombinant gene sequences for synthesizing a protein having the biological activity of the PilC protein. Furthermore, the invention relates to DNA recombinant methods for the production of proteins having the biological activity of the PilC protein as well as the molecular-biological tools required therefor. In addition, the invention relates to proteins having the biological activity of the PilC protein and its antibodies. Other embodiments of the invention are pharmaceutical compositions comprising the mentioned proteins or antibodies. Preferably, these pharmaceutical compositions serve as vaccines for the immunization against pathogenic bacteria bearing type 4 pili. The invention also relates to kits for the detection of bacteria bearing type 4 pili or antibodies directed against them comprising the mentioned proteins or antibodies. Finally, the invention relates to cellular receptors for bacteria bearing type 4 pili and analogues thereof.

A crucial step in the occurrence and the manifestation of any infection is the attachment of the pathogen to certain molecular structures (receptors) of the host organism. The pathogen's structures responsible for attachment shall be referred to as adhesins. It is possible that multiple molecular interactions between adhesins of the pathogen and receptors of the host organism are necessary for the occurrence and/or the manifestation of an infection. On the other hand, it is thinkable that blocking one single molecular interaction between an important adhesin and a receptor is sufficient to prevent an infection. Blocking molecular adhesin-receptor interactions is a possible form of prevention and/or therapy of infectious conditions. Prophylactic approaches include, for instance, the formation of antibodies directed specifically against the adhesin and block any interaction with its receptor by active immunization (vaccination). However, the interaction may principally also be prevented in the sense of a prophylactic or therapeutic measure by passively administered antibodies or other substances, for instance adhesin or receptor analogous substances, which shall be referred to under the generic term inhibitors. Important adhesins of numerous gram negative pathogens are pili (also termed fimbriae or fibrillae). They are polymeric structures forming fine thread-like appendages to the surface of the bacteria. Pili make it possible for the bacteria to attach to specific receptors of the host organism via the adhesins contained in the pili. In some cases it was shown that the loss of the pili leads to the pathogen's loss of infectiousness. This loss of infectiousness can be explained by the loss of the capability to form attachments. Therefore, blocking the molecular interaction between pilus adhesin and receptor can avoid or stop the infection of the host organism.

In gram negative bacteria, different types of pili are known. The majority of all known pili are heteropolymeric structures comprising several subunits, one main subunit and other inferior subunits which are present in only a few copies. In some well examined cases the inferior subunits are the actual adhesive structures (adhesins), whereas the main subunit which is present in a high number of copies takes over the function of a framework (Lindberg et al., Nature 328, 84-87, 1987). Numerous pathogenic gram negative bacteria species form type 4 pili, which are also referred to as N-Me-Phe or type IV pili. They include the pathogenic Neisseria species N. gonorrhoeae and N. meningitidis, causing gonorrhoe and bacterial meningitis, respectively, in humans. However, there is no effective vaccine against N. gonorrhoeae so far. The capsula-specific vaccines against some sero groups of N. meningitidis, however, are available; unfortunately they offer only partial protection and are considered immunologically problematical. Thus, these infections are usually treated with antibiotics; however, the ever increasing resistance of the pathogens to antibiotics causes problems. The development of alternative methods of treatment is therefore urgent. Another important pathogen forming type 4 pili in humans is Pseudomonas aeruginosa (Sastry et al., FEBS Letters 151, 253-255, 1983), which is a central problem for patients suffering from cystic fibrosis, immunodeficiencies and in connection with septic infections. Effective vaccines and/or inhibitors of this pathogen are not yet available; problematic is above all the increased spreading of multi-resistant strains. Alternative methods of treatment are thus urgently required in this field too. More examples of important pathogens forming type 4 pili are enteropathogenic Escherichia coli (EPEC; Giron et al., Science 254, 710-713, 1991), Vibrio cholerae (Shaw et al., Infect. Immun. 58, 3042-3049, 1990), Bacteroides nodosus (McKern et al., FEBS Letters 164, 149-153, 1983), Moraxella bovis (Marrs et al., J. Bacteriol. 163, 132-139, 1985) and other pathogens, causing diseases in humans and animals and vaccines against which are searched for intensively. Type 4 pili are defined by the structure of their main subunit, usually referred to as pilin; besides, there are specific terms for the pilin main subunit for individual species of bacteria, e.g. PilE for N. gonorrhoeae or PilA for Pseudomonas aeruginosa. The pilin's structure of the type 4 pili differs substantially from that of main subunits of other pilus types, such as the group of pap-like pili (Baga et al. J. Bacteriol. 157, 330-333, 1984). Characteristics of the pilin of type 4 pili are (a) the short, positively charged, aminoterminal signal sequence of the pilin's preform (exception V. cholerae type 4 pilin), (b) the hydrophobic amino terminal region of the mature pilin that exhibits strong sequence homology between different type 4 pilins, (c) the modification of the amino terminal Phe residue of the mature pilin by means of a methyl group in N position (N-Me-Phe), (d) two Cys residues in the carboxy terminal region of the pilin that form a loop and (e) a property termed twitching motility.

So far, PilC proteins were detected as components of N. gonorrhoeae and N. meningitidis. Up to now, an assembly function in the pilus biogenesis was considered to be a function of these PilC proteins (Jonsson, Dissertation, New Series No. 322, University of Umea, ISSN 0346-6612). However, these works never indicated a possible role as an important adhesin. In other tests, scientists succeeded in isolating mutants of N. gonorrhoeae which did still form pili but no longer exhibited an adherence to epithelial cells (Rudel et al., Mol. Microbiol. 6, 3439-3450, 1992). These mutants turned out to be phase-variant strains that had stopped forming PilC proteins. A direct function of the Neisseria PilC proteins could not be derived from these experiments. However, the experiments showed that the assembly of the Neisseria pili can take place also if no PilC proteins are present. Scientists had been successful in cloning a single PilC-protein encoding gene in E. coli. This was achieved by means of the gel electrophoretic purification of PilC protein from isolated Neisseria pili (Jonsson et al., EMBO J. 10, 477-488, 1991). The gel electrophoretically purified PilC protein was used for the recovery of antiserum. The gel electrophoretically purified PilC protein had no biological activity in the sense of this invention. The corresponding antiserum thus does not have the property of this invention to block the attachment of piliated Neisseria to epithelial cells. Using the antiserum, scientists at first succeeded in identifying an E. coli phage clone carrying a partial PilC-encoding gene. An E. coli clone with an intact PilC-encoding gene could be identified by means of the partial PilC-encoding gene using DNA hybridization (Jonsson et al. EMBO J. 10, 477-488, 1991). This recombinant PilC-encoding gene was translationally inactive due to its variable, homopolymeric sequence so that a synthesis of biologically active PilC protein did not take place. The nucleotide sequence of this first PilC-encoding gene (pilcl) from the N. gonorrhoeae MS11 strain is known; a partial sequence of a second gene (pilC2) from this strain is known as well (Jonsson et al., EMBO J. 10, 477-488, 1991; Jonsson, Dissertation, New Series No. 322, University of Umea, ISSN 0346-6612). However, none of these genes has made it possible to produce PilC.

Thus, the invention essentially is to solve the technical problem to provide biologically active proteins having the biological activity of the PilC protein. This technical problems is solved by providing the embodiments characterized in the claims.

Thus, the invention relates to recombinant gene sequences for synthesizing a protein having the biological activity of the PilC protein, whose sequence portion encoding the phase-variable signal peptide and containing a homopolymeric nucleotide sequence is characterized by the two following modifications:

(a) modification of the homopolymeric nucleotide sequence to form an invariable heteropolymeric nucleotide sequence or

(b) substitution of the phase-variable signal-peptide encoding sequence portion against another, non-phase-variable nucleotide sequence that encodes a signal peptide compatible with the secretion of the PilC protein

so that the expression of the recombinant gene sequence in a host cell is made possible unaffected by phase variations.

These DNA-sequences of this invention serve for the expression of proteins having the biological activity of the PilC protein. In this invention, the term “biological activity of the PilC protein” relates to the encoded protein's capability to support the assembly of type 4 pili, to mediate the attachment of bacteria bearing type 4 pili to cellular receptors or to the immunological suitability for the induction of antibodies for bacteria bearing type 4 pili, which compete with the attachment of the bacteria to their cellular receptors and preferably block the attachment. According to this invention, the term “protein” relates to naturally occurring proteins or to modifications or fragments thereof exhibiting the above-mentioned biological activity. The term “PATHOGENIC BACTERIA BEARING TYPE 4 PILI” as used in this invention refers to bacteria that, on the one hand, are in a causal relationship with the pathogenesis of diseases and, on the other hand, as an essential element of their pathogenic property, form type 4 pili, which are necessary for the attachment of the bacteria to cellular receptors in the infected host organism.

“HOMOPOLYMERS” are nucleotide sequences consisting of a sequence of identical nucleotides (e.g. 5′-CCCCCCC-3′). In this invention, “HOMOPOLYMERIC NUCLEOTIDE SEQUENCES” are defined by their property to spontaneously or inducedly add one or several identical nucleotides to the existing homopolymeric nucleotide sequence or lose the same therefrom. The addition and/or loss of identical nucleotides in homopolymeric nucleotide sequences results in a “PHASE VARIATION”. This phase variation is caused by a RecA-protein independent process, which takes place substantially spontaneously (Robertson & Meyer, Trends Genet. 8, 422-427, 1992). The changes in the nucleotide sequence underlying the phase variation effect the translational reading frame of a gene and therefore the formation of the intact gene product. In the sense of this invention phase variation is undesired because under the control of a strong promoter, phase variation of the PilC encoding DNA will cause a changed reading frame and thus a loss of the formation of the desired protein having the biological activity of the PilC protein. An “INVARIABLE HETEROPOLYMERIC NUCLEOTIDE SEQUENCE” in the sense of this invention is therefore a nucleotide sequence derived from a homopolymeric nucleotide sequence by addition or exchange of non-identical nucleotides (i.e. in the case of the sequence 5′-GGGGGGGGGGGGG-3′ (SEQ. ID NO.:4) the nucleotides A, C and/or T) and, due to these modifications, has become “NON PHASE-VARIABLE”, i.e. exhibits no phase variations. Due to the genetic code, it is possible to modify the homopolymeric nucleotide sequence such that the encoded amino acid sequence either remains unchanged or is also changed.

A “SIGNAL PEPTIDE” as used in this invention is an amino acid sequence at the amino terminus of the preform of a protein secreted from gram negative bacteria. A signal peptide makes the secretion of a protein via the general export path of the internal bacteria membrane possible (Pugsley, Microbiol. Rev. 57, 50-108, 1993). The phase-variable signal-peptide encoding portion of the gene sequence of this invention is modified (a) by modification of its homopolymeric nucleotide sequence (see above) or (b) by substitution of the phase-variable signal-peptide encoding portion, which, due to the comprised homopolymeric nucleotide sequence phase, is variable. The substitution is a partial or a complete exchange of the signal-peptide encoding sequence portion by another signal-peptide encoding sequence that makes the secretion of the PilC protein via the mentioned general export path possible, contains no phase-variable homopolymeric nucleotide sequence and is altogether a non-phase-variable nucleotide sequence. The changes (modification or substitution) are carried out with the aim to make the expression of the gene sequence in a host cell possible without any influences by phase variations in order to guarantee the formation of PilC protein under stable conditions and in large amounts (production of surplus). Hybridization of chromosomal DNA of, for instance, N. gonorrhoeae with a complete pilC gene as a probe indicate that two related pilC genes exist in the chromosome of this species. However, if subgenic fragments of a pilC gene are used as a probe, more cross hybridizing genes can be rendered visible that are also pilC genes which, however, are only in a distant relationship. The detection of such distantly related pilC genes is based on the cross-hybridization of constant regions of the DNA sequence between two or more related pilC genes. Constant regions of the DNA sequence can be defined by means of a sequence comparison between two related genes. The definition of constant regions of the DNA sequence thus results in the possibility to identify also distantly related pilC genes. The repeated sequence comparison with such a distantly related gene, in turn, results in new constant regions of the DNA sequence which, again, can be used for the identification of pilC genes, etc. This way, all members of the pilC gene family within and outside a bacteria species can gradually be detected.

The recombinant gene sequences of this invention render the production of proteins having the biological activity of the PilC protein in considerable amounts possible. This also makes the general identification of inferior subunits of the type 4 pili and their reliable characterization as adhesins possible. The invention allows in particular for the detection of the PilC proteins of pathogenic Neisseria (N. gonorrhoeae and N. meningitidis) in their function as important adhesins. Furthermore, the invention allows for the detection of PilC analogous proteins of other bacteria species forming type 4 pili. The detection according to this invention of the adhesin function of an inferior subunit of a type 4 pilus and/or PilC analogous proteins has not been described so far for any bacteria species producing type 4 pili. The term “PilC analogous protein” relates exclusively to the structural relationship (of nucleotide and amino acid sequence) with the PilC proteins of the pathogenic Neisseria and to the analogous function with the Neisseria PilC proteins as receptor binding adhesins. The PilC analogous proteins of other bacteria species forming type 4 pili of this invention are not necessarily identical with or related to the proteins referred to as PilC in literature (for instance the known PilC protein of Pseudomonas aeruginosa (Nunn et al., J. Bacteriol. 172, 2911-2919, 1990) is not a PilC analogous protein of this invention).

The main subunit of the type 4 pili was erroneously considered an important adhesin in some cases (Rothbard et al., PNAS (USA) 82, 919, 1985; Paranchych, In: The Bacteria Vol. XI, Molecular Basis of Bacterial Pathogenesis, Academic Press, 61-78, 1990 and citations therein). Based on these findings and/or hypotheses, numerous attempts have been made to block the adherence of bacteria to human or animal cells using antibodies and/or adherence blockers or to stop a bacterial infection by means of vaccination using the type 4 pilus main subunit. Despite partial success (Paranchych, In: The Bacteria Vol. XI, Molecular Basis of Bacterial Pathogenesis, Academic Press, 61-78, 1990 and citations therein; Tramont, Clin. Microbiol. Rev. 2, 74-77, 1989 and citations therein) it has not yet been possible to develop a widely effective vaccine or a widely effective inhibitor based on the main subunit of the type 4 pili. There are two possible explanations: (a) The main subunit of a type 4 pilus comprises no important adherence functions so that the attachment of the pili to the receptor is not blocked and/or (b) the vaccines or the inhibitor are not effective or not widely enough effective due to the structural variability of the pilin main subunit.

The latter explanation relates to the assumption that a vaccine directed against pilin might cause a complete loss of the pili's capability to adhere, independent of whether or not pilin is an adhesin. The effect of the antibodies directed against pilin might affect the structure function of the pilin and thus indirectly the adherence properties of the pili altogether. That this way obviously does not lead to success (Johnson et al., J. Infect. Dis. 163, 128-134, 1991) is mainly due to the mentioned structural variability of the pilin. It is known that pilin of bacteria species forming type 4 pilus exhibits inter-strain specific and/or intra-strain specific structural variability. This structural variability is the reason for an indirect blocking of the adherence by means of antibodies directed against the variable main pili subunit not being widely effective but rather being restricted to that certain strain or the variant. This is why it has been impossible to develop a widely effective vaccine on the basis of the pili main subunit (pilin).

The PilC proteins that can now be produced using the gene sequences of this invention, e.g. those of pathogenic Neisseria, also show structural variability, as can be seen, for instance, from the comparison of the encoding nucleotide sequences (FIG. 4, SEQ. I.D. Nos. 1-3). Contrary to the variability of the pilins, however, the variability of the PilC adhesins is markedly less and has no (or negligible) effect on the function of the PilC proteins, namely the molecular interaction with the receptor. This statement is supported by the competition experiments with biologically active PilC protein (Tab. 2) since bacteria forming different pilin molecules and/or PilC proteins can be displaced using the same PilC protein. Thus, although PilC proteins varying in structure are formed within one species, these PilC proteins of one species recognize the same or only a few different receptors in the host organism. It is therefore possible to develop a widely effective vaccine and/or widely effective adherence inhibitors based on only a few variant forms of the PilC proteins of one species. In addition, this invention makes it possible to develop widely effective receptor analogues based on only one or a few receptors. These possibilities also apply to the PilC-analogous adhesins formed by bacteria forming type 4 pili that do not belong to the species Neisseria. It may be assumed that the cell, tissue and host tropism of a species is largely determined by the interaction of the adhesins with their corresponding cellular receptors. These tropisms are very marked in many pathogens, particularly also in bacteria forming type 4 pilus. From this fact it can be inferred that also the PilC analogous adhesins of this invention of one species with their defined tropisms interact only with one or a few cell, tissue and host specific receptors. This involves the possibility to develop widely effective vaccines and other inhibitors of an infection corresponding to the use of the PilC adhesins of the Neisseria based on the PilC analogous adhesins of other species and/or their receptors. One important aspect of the present invention was to detect the function of the PilC proteins as important adhesins in connection with the occurrence of an infection. In order to do so, it was necessary to recover biologically active PilC protein in pure form and to prove its biological activity in suitable test systems.

For producing a recombinant gene sequence of this invention the complete pilC2 gene from the N. gonorrhoeae MS11 strain was isolated based on the information available on PilC1 and its gene and cloned into E. coli. In order to produce the protein of this invention having the biological activity of a PilC protein of the genus Neisseria from this gene, the phase-variable, signal-peptide encoding, homopolymeric sequence portion of the pilC2 genes was modified such that the expression of the recombinant genes in a host cell is rendered possible unaffected by phase variation. This was achieved by modification of the homopolymeric sequence portion to form a heteropolymeric sequence using suitable oligo nucleotides by means of the polymerase chain reaction (PCR) (Example 2).

In a preferred embodiment, the gene sequence of this invention can be obtained by modification of a DNA sequence stemming from a pathogenic bacterium bearing type 4 pili. This bacteria group was characterized in detail above. Examples of such bacteria are Neisseria, particularly N. gonorrhoeae and N. meningitidis, pseudomonades, particularly P. aeruginosa, enteropathogenic Escherichia, particularly E. coli (EPEC), Vibrio cholerae, Bacteroides nodosus and Moraxella bovis.

In a more preferred embodiment of this invention, the gene sequence is obtained by modification of a DNA sequence from a bacterium of the genus Neisseria, preferably Neisseria gonorrhoeae or Neisseria meningitidis.

The gene sequences of the N. gonorrhoeae pilC2 gene (SEQ. ID. NO.:1) and of the N. meningitidis pilC A1493 (SEQ. ID. NO.:2) gene shown in FIG. 4 of this invention are especially preferred. The shown sequences start at position 1 with the codon ATG coding for the first amino acid (Met). The region coding for the signal peptide stretches from positions 1 to 99 based on gene pilC2. The phase-variable homopolymeric sequence portion is contained therein, stretching from positions 79 to 91. The constant nucleotides of the shown sequences are marked with asterisks. Individual constant sequence portions of the genes pilC1 and pilC2 are separately shown in Table 3.

DNA hybridization experiments with the complete pilC1 gene, with fragments of the pilC1gene obtained by means of restriction endonucleases, or with the previously known gene portion of the pilC2 gene of N. gonorrhoeae MS11, indicated the existence of 2 (Jonsson et al., EMBO J. 10, 477-488, 1991) and/or maximal 3 (Bihlmaier et al., Mol. Microbiol. 5, 2529-2539, 1991) related pilC genes within this strain. The determination of the nucleotide sequence of the second complete pilC gene of this invention (pilC2) and the comparison of the two pilC nucleotide sequences (FIG. 4, SEQ. ID. NOs.:1-3) make it possible according to this invention to determine preserved regions of the pilC genes (Table 3). Corresponding subgenic, preserved fragments and/or oligo nucleotides of a pilC gene can then, unlike complete genes and/or larger gene fragments, be used as hybridization probes due to their corresponding homologies to the genes related to preserved nucleotide sequences in order to identify and isolate such related genes altogether. Thus, the gene sequence of this invention is available in another embodiment by modification of a DNA sequence that hybridizes to a constant region of the DNA sequence of FIG. 4, SEQ. I.D. NOs. 1-3, and/or Table 3 and codes for a protein having the biological activity of the PilC protein.

Another subject-matter of the invention are thus gene sequences that hybridize to a constant region of the gene sequence shown in FIG. 4, SEQ. I.D. NOs. 1-3, and/or Table 3, code for a protein having the biological activity of the Pilc protein and stem from a pathogenic bacterium bearing type 4 pili that is not of the genus Neisseria.

According to this invention the length of a homopolymeric nucleotide sequence modified to form a heteropolymeric nucleotide sequence amounts to 5 or more nucleotides. The sequence examples given in FIG. 4 (SEQ. I.D. NOs. 1-3) are 12 G (pilC1), 13 G (pilC2), 9 G (pilC A1493); cf. position 79 to position 91 based on the gene sequence pilC2.

In another preferred embodiment of this invention, the modified gene sequence codes for a protein having the biological activity of the PilC protein and exhibiting an oligo histidine portion suitable for its purification. This oligo histidine portion preferably contains 6 histidine residues (His₆). The presence of the His₆ peptide makes it possible to selectively bind the PilC protein of this invention to a nickel-NTA (Ni-nitrilo triacetic acid)-agarose column (Hochuli et al., J. Chromat. 411, 177-184, 1987; Hochuli et al., Bio/Techno. 6, 1321-1325, 1988) with the eluted protein being pure PilC protein.

In a more preferred embodiment of this invention, the oligo histidine region is at the N terminus or the C terminus of the mature form of the encoded proteins. This ensures a spatial structure less liable to disturbances of the proteins.

In another embodiment, the invention relates to recombinant vectors that comprise a gene sequence of this invention. Examples of such vectors are vectors pBR322 and pBA which replicate in E. coli, vectors based on the bacteriophages M13, fd or lambda, broad host range vectors, shuttle vectors that correspond to Hermes vectors (Kupsch et al., filed for publication) which make it possible to incorporate cloned genes into the DNA of the recipient Neisseria cell as well as the plasmid ptetM25.2, which can be used for the conjugative transfer of genes between Neisseria (Kupsch et al., filed for publication).

In a preferred embodiment of the vectors of this invention, the mentioned gene sequence is controlled by a promoter. Examples of suitable promoters according to this invention are promoters that are functional in gram negative bacteria and, in particular, inducible promoters. In an especially preferred embodiment of this invention, the promoter is Ptrc, which can be repressed in Neisseria and E. coli as well as induced in the presence of IPTG in the presence of an expressed lacl^(q) gene.

In another embodiment, the invention relates to host cells that comprise one or several recombinant vectors of this invention. The host cells of this invention serve for replication, transcription and translation of the gene sequence of this invention for the synthesis of a protein having the biological activity of the PilC protein. They are preferably gram negative bacteria which render it possible to secrete the synthesized protein via the inner membrane and fold it correctly. Examples of such host cells are E. coli K12 and other gram negative bacteria, for which suitable cloning vectors are available. Preferably, the host cell of this invention is a non-piliated Neisseria strain, which—like N. gonorrhoeae N174—has lost its capability to form its pili due to a defective pilE gene. The pilE gene codes for the main subunit (pilin) of the Neisseria pili. Due to the defective pilE gene, no pilin is synthesized making the recovery of biologically active PilC protein absolutely free of pilin possible.

In another embodiment, the invention relates to methods for the production of a substantially pure protein having the biological activity of the PilC protein, comprising culturing a host cell of this invention under suitable conditions and purifying the protein.

In a preferred embodiment of the production method of this invention, the purification of the protein having the biological activity of the PilC protein takes place by means of an affinity chromatography, preferably an affinity chromatography, wherein the oligo histidine portions contained in the protein of this invention are used for attachment of the proteins.

In another embodiment, the invention relates to substantially pure protein having the biological activity of the PilC protein obtainable according to the described methods of this invention. Furthermore, the invention relates to substantially pure protein having the biological activity of the PilC protein encoded by a gene sequence of this invention. The proteins having the biological activity of the PilC protein of this invention considerably differ from the state of the art in that they are biologically active, whereas PilC proteins known from the state of the art could not be provided in biologically active form. The PilC protein of this invention exhibits high purity and is particularly free of pilin. Besides, the proteins having the biological activity of the PilC protein of this invention can be produced in amounts large enough for instance for the production of vaccines. This was not possible with traditional production and purification methods. Depending on the expression system the proteins having the biological activity of the PilC protein obtainable according to this invention differ also structurally from the known PilC proteins, which are not biologically active. Recombinant PilC proteins for instance may be marked by additional, deleted, inverted or otherwise modified amino acid sequences.

In another embodiment, the protein having the biological activity of the PilC protein of this invention is marked such that it can be detected by common methods. Examples of such markers in recombinant PilC proteins are amino acid sequences that can be identified by means of known biological and chemical methods. A biological method e.g. relates to sequences that can be detected by means of an antibody; a chemical method e.g. relates to sequences that can be detected by the formation of an Ni-NTA complex.

In another embodiment, the invention relates to antibodies to proteins having the biological activity of the PilC protein of this invention, wherein the antibodies inhibit attachment of the protein to the corresponding receptor. These antibodies of the invention are monoclonal or polyclonal antibodies. The invention also relates to common fragments of these antibodies, e.g. F_(ab) or F_((ab)2) fragments. Furthermore, the invention relates to antibodies having the mentioned attachment activity that can be produced by recombinant methods as well as for instance bivalent antibodies. Furthermore, the invention relates to anti-idiotypical antibodies having the attachment activity of the PilC protein to cellular receptors or the immunological activity of the PilC protein for the induction of antibodies to bacteria bearing type 4 pili that inhibit attachment of the protein to the corresponding receptor.

In another embodiment, the invention relates to pharmaceutical compositions comprising a protein of this invention or an antibody of this invention, optionally in combination with a pharmaceutically acceptable carrier. Preferably the pharmaceutical compositions of this invention are vaccines, more preferably vaccines for the immunization against pathogenic bacteria bearing type 4 pili. Most preferably they are vaccines against bacteria of the genus Neisseria, preferably Neisseria gonorrhoeae or Neisseria meningitidis. These pharmaceutical compositions make a reliable prevention of gonorrhoe or meningitis possible. The surprising usability of the proteins having the biological activity of the PilC protein of this invention for these medical indications is due to the novel finding of this invention that the PilC proteins are the adhesins of the pathogenic bacteria bearing type 4 pili and not, as erroneously assumed in the state of the art, the pilin main subunits, such as PilE in N. gonorrhoeae.

Furthermore, the invention relates to kits for the detection of bacteria bearing type 4 pili or antibodies directed against them comprising a protein of this invention or an antibody of this invention. Preferably these kits are suitable for the detection of bacteria of the genus Neisseria, preferably Neisseria gonorrhoeae or Neisseria meningitidis. Examples of the detection processes that may be carried out using the kits of this invention are radio immuno assays or ELISAs (enzyme-linked immuno assays).

In another embodiment, the invention relates to cellular receptors for bacteria bearing type 4 pili that have the capability to attach to a protein of this invention. Such receptors may be isolated and identified by means of the proteins of this invention. This way, it is possible to couple a PilC protein to a matrix and to purify the receptor by means of affinity chromatography at the attached PilC protein and maintain the receptor in a pure form. With the purified receptor of this invention and the PilC protein of this invention, it is possible to study the physico-chemical interaction between the two purified component and to draw conclusions regarding the type of interaction. The two purified components particularly serve to search for inhibitors of the interaction between PilC protein and its receptor. These inhibitors at the same inhibit the corresponding bacterial infections. Examples of such inhibitors are synthetic peptides or other chemical substances that represent the structure and attachment properties of the adhesins (of the PilC and/or PilC analogous proteins) or of the receptors. The latter are receptor analogues. With the PilC protein of this invention it is also possible to identify the corresponding receptor genetically. For instance, animal/human cells that do not form the receptor can be transfected with the cDNA of cells that do form the receptor. From transfected cells, which now do form the receptor, the cDNA coding for the receptor may be isolated, and by means of the structural analysis of the cDNA, the structure of the receptor of this invention can be recognized. The structure of the receptor of this invention provides information on the predetermined recovery of inhibitors by means of known genetic-engineering or chemical methods. Besides, the isolation of the cDNA of the receptors makes it possible to obtain the receptor by means of genetic-engineering methods. In a preferred embodiment, the receptor stems from pathogenic Neisseria.

The Figures show:

FIG. 1: Restrictions maps of the plasmids pTR27 (FIG. 1A) and plS26 (FIG. 1B). Plasmid pTR27 comprises the natural pilC2 gene of the N. gonorrhoeae strains MS11-N133. Starting from this plasmid, a gene sequence of this invention was created in several steps (Example 2; FIG. 2), which sequence is present in cloned form in the plasmid plS26. Plasmid plS26 is a Hermes construct (Kupsch et al., filed for publication), which makes both possible the replication in E. coli and the insertion of the recombinant gene sequence of this invention into the conjugative ptetM25.2 plasmid in N. gonorrhoeae. This insertion takes place by transferring the gene sequence contained in the shuttle box by means of double homologous recombination in the two dotted regions of plS26 with ptetM25.2.

FIG. 2: Construction scheme of the recombinant gene sequence for synthesizing the PilC protein of this invention. The description of the work carried out can be found in Example 2. The DNA region shown in this Figure corresponds to the 5′-terminal region of the pilC2 genes contained in pTR27 (cf. FIG. 1). The terms “TR . . . ” refer to the used oligo nucleotides (Example 2). (A) Modification of the phase-variable signal-peptide encoding sequence portion containing a homopolymeric nucleotide sequence. (B) Insertion of a His₆-peptide encoding nucleotide sequence. (C) Explanations regarding (A and B) (SEQ. I.D. NOs. 33-40).

FIG. 3: Analytical gel electrophoresis of purified pili of the N. gonorrhoeae wild-type strain N137 (1) and the PilC negative N. gonorrhoeae double mutant N474 (2), as well as of the biologically active PilC2 protein of this invention (3). The isolation of the pili is carried out according to Jonsson et al. (1991); the recovery of the PilC2 protein of this invention is described in Example 3.

FIG. 4: (SEQ. I.D. NOs. 1-3). Nucleotide sequences of the natural pilC gene. (A) Comparison of the nucleotide sequences of the genes pilC1 and pilC2 of Neisseria gonorrhoeae MS11-N133; (B) Comparison of the nucleotide sequences of the pilC1 genes of Neisseria gonorrhoeae MS11-N133 with the partial gene sequence of a pilC gene of Neisseria meningitidis A1493; (C) Comparison of the nucleotide sequence of the pilC2 gene of Neisseria gonorrhoeae MS11-N133 with the partial gene sequence of a pilC genes of Neisseria meningitidis A1493. Examples preserved regions of this invention are marked by asterisks. The modifications carried out for the construction of the recombinant gene sequence of this invention are shown in FIG. 2.

The examples explain the invention in more detail.

EXAMPLE 1

Isolation of the pilC2 Genes of N. gonorrhoeae

Based on the partial sequences of pilC1 and pilC2 published by Jonsson et al. (EMBO J. 10; 477-488, 1991), specific oligo nucleotide probes were constructed (for pilC1: CG31 CGATGGCGCAAACCCATCAA (SEQ. ID. NO.:5); for pilC2: CG32 CGCAGGCGCAAACCCGTAAA) (SEQ. ID. NO.:6), by means of which both pilC genes could be isolated from a plasmid gene bank of genomic DNA of Neisseria gonorrhoeae MS11. For this purpose both probes were radioactively marked using DNA kinase at the 5′ end and hybridized against approx. 30000 clones of the gene bank. The positive clones were isolated, again hybridized against the radioactively marked probes and finally characterized. One of the obtained plasmids (pTR27, cf. FIG. 1) contained the entire pilC2 gene, however lacking the promoter for synthesizing the PilC protein. The pTR27 is the basic construct for the determination of the DNA sequence of the pilC2 gene and for the modification of the DNA and protein sequences using genetic engineering methods (cf. Example 2 and Example 6).

EXAMPLE 2

Construction of a N. gonorrhoeae Strain Producing a Surplus of PilC Protein

The modification of the homopolymeric nucleotide sequence, which consisted of 13 G-nucleotides in the case of the cloned pilC2 gene, was achieved in two steps by predetermined mutagenesis by means of the polymerase chain reaction (PCR). In these reactions, the plasmid pTR27 (cf. Example 1, FIG. 1) served as template. The first step (first PCR) comprised two separate PCR reactions of the pilC2 genes having the primer pairs TR12 (TTGGATCCGACGTCCGAAAAGGAAATACGATG, SEQ. ID. NO.:1) and TR28 (GCTCCACCACCTCCGCCGGTATGGGAAAAC, SEQ. ID. NO.:8), as well as TR27 (ACCGGCGGAGGTGGTGGAGCGCAGGCGCAAACCCGT, SEQ. ID. NO.:9) and TR23 (TGTGTCTCTGCATATGACG, SEQ. ID. NO.:10) (FIG. 1). The PCR reactions (25 cycles of 1 minute at 94° C., 2 minutes at 50° C. and 1 minute at 72° C., each) were carried out in a Perkin Elmer Cetus Thermal Cycler and contained 100 pmole primer, approx. 1 ng pTR27 and 2 units VentR™ polymerase (New England Biolabs) in a volume of 100 μl, each. The oligo nucleotide TR28 hybridized directly before, the oligo nucleotide TR27 directly after the homopolymeric nucleotide sequence region, which resulted in neither the first nor the second PCR fragment containing the homopolymeric nucleotide sequence region. Instead, due to the 5′ extensions of the oligo nucleotides TR28 and TR27, fragments 1 and 2 contained an invariable, heteropolymeric nucleotide sequence that codes for the same amino acids as the original homopolymeric nucleotide sequence. Fragments 1 and 2 of the first PCR were separated by means of agarose gel electrophoresis and extracted using GENECLEAN (BIO 101). The purified fragments were merged in the second PCR reaction to form a fragment by now amplifying the oligo nucleotides TR12 and TR23 in a reaction (FIG. 2). The conditions of the second PCR were selected as follows: 100 pmole primer, fragment 1 and fragment 2 in equimolar amounts (50 ng each) and 2 units of the VentR™ polymerase. Unlike during the first PCR, during the second PCR 15 cycles were carried out under the same conditions. The correct exchange of an invariable, heteropolymeric nucleotide sequence for the variable homopolymeric nucleotide sequence was checked by an analysis of the DNA sequence. The obtained PCR product was replaced as a BamHI/NdeI digested fragment by the corresponding BamHI/NdeI fragment of the pTR27 vector so that plasmid pTR81 was obtained. In order to make purification of the PilC protein by nickel chelate affinity chromatography possible (Hochuli et al., Journal of Chromatography 411, 177-184, 1987; Hochuli et al., Bio/Technology 6, 1321-1325, 1988), the DNA sequence coding for a peptide (His₆) comprising six histidine residues was inserted in the pilC gene. Cloning of the DNA sequence encoding His₆ was carried out analogously to the above-described technique of controlled PCR mutagenesis (FIG. 1). In the first PCR, the plasmid pTR81 served as template. In separate reactions, the fragment 1 was amplified with the oligo nucleotide pair TR12 and TR71 (GTGATGATGGTGGTGATGGGTTTGCGCCTGCGCTCCA, SEQ. ID. NO.:11) and the fragment 2 with the oligo nucleotide pair TR23 and TR70 (CATCACCACCATCATCACCGTAAATACGCTATTATC, SEQ. ID. NO.:12). The oligo nucleotide TR71 paired with the codon for Thr₃₅ starting at the (−) strand; the oligo nucleotide TR70 paired with the codon for Arg₃₆ starting at the (+) strand (cf. FIG. 2). Due to their 5′ extensions, the two oligo nucleotides coded for the His₆ sequence that was inserted between the codons Thr₃₅ and Arg₃₆ in pilC2 by way of the second PCR (cf. FIG. 2). The BamHI/NdeI digested PCR product of the second PCR was replaced by the corresponding BamHI/NdeI fragment of pTR27 (cf. Example 1). The resulting construct is called plS25. The DNA sequence analysis confirmed the correct insertion of the His₆ peptide between the amino acids Thr₃₅ and Arg₃₆.

The inducible overexpression of the pilC2 gene with the non-phase-variable nucleotide sequence and His₆ encoding nucleotide sequence was achieved by cloning the BamHI/HindIII fragment from the plS25 into the Hermes-8 vector (Kupsch et al., filed for publication) at first in E. coli K12 under the control of the Ptrc promoter (plS26, cf. FIG. 1), thus achieving the isopropyl-β-D-thiogalactoside (IPTG) inducible expression of the recombinant pilC2 genes under the control of the P_(trc) promoters. By transformation of N. gonorrhoeae N219 and allelic exchange the shuttle box of plS26 containing the recombinant pilC2 gene was inserted into the conjugative plasmid ptetM25.2. This way the recombinant gene could be conjugatively transferred in the pilin-free N. gonorrhoeae strain N174, which, due to the deletion of the pilE gene coding for pilin, cannot be transformed. The resulting N. gonorrhoeae strain ISN19 synthesized after induction with IPTG pilin-free PilC2 protein in large amounts.

EXAMPLE 3

Isolation of Pilin-free, Biologically Active PilC Protein

For the recovery of the biologically active PilC protein of this invention the strain ISN19 was spread on 30 small GC-agar plates (9 cm in diameter) that contained an additional 5 μg/ml tetracycline and 100 μM IPTG and incubated for 20 hrs. at 37° C., 5% CO₂. The GC-agar plates contained the substances necessary for the growth of N. gonorrhoeae, particularly 36 g GC-Agar-Base (Becton, Dickinson & Company) which was autoclaved in 1 l water and to which 10 ml sterile-filtered vitamin mix were added. The vitamin mix particularly contained 0.01 g vitamin B12, 1 g adenine, 0.03 g guanine, 10 g glutamine, 0.1 g cocarboxylase, 0.03 g thiamine, 25.9 g L-cysteine, 1.1 g L-cystine, 150 mg arginine, 0.5 g uracil, 0.02 g Fe(NO₃)₃, 0.25 diphosphopyridin nucleotide, 0.013 g p-amino benzoic acid and 100 g dextrose dissolved in 1 l water. The bacteria were resuspended in 30 ml 50 mM TRIS.Cl, 0.15 M NaCl, pH 8.0 using cotton swabs and centrifuged for 15 minutes at 4,000 revolutions per minute (rpm) and 4° C. in a SS34 rotor (Sorval). The pellet was resuspended in 30 ml 50 mM TRIS.Cl, 0.15 M NaCl, pH 8.0, and the bacteria were broken up by addition of one spatula tip lysozyme and 5 mM ethylene diamine-tetraacidic acid-disodium salt-dihydrate (EDTA) by means of ultrasonic treatment. The lysed bacteria were pelleted for 20 minutes at 5,000 rpm and 4° C. in the SS34 rotor. The membranes were pelleted from the resulting supernatant for 60 minutes at 20,000 rpm and 4° C. in the SS34 rotor and then resuspended in 10 ml 50 mM TRIS.Cl, 0.15 M NaCl, 10% glycerin, 10 mM MgCl₂, pH 8.0 and 2% Triton X100. The suspension was incubated for 45 minutes at 37° C. and again centrifuged for 60 minutes at 20,000 rpm and 4° C. The membrane pellet, which consisted mainly of outer membrane, was washed once with 10 ml 50 mM TRIS.Cl, 0.15 M NaCl, pH 8.0 and again pelleted for 60 minutes at 20,000 rpm. Now the pellet was suspended in 10 ml 50 mM TRIS.Cl, 0.15 M NaCl, 10 mM MgCl₂, 10% glycerin, pH 8.0 and 2% LDAO (N,N-dimethyl dodecyl amine-N-oxide) and incubated for 60 minutes at 37° C. After centrifugation for 60 minutes at 20,000 rpm (4° C.) in the SS34 rotor the supernatant in which the biologically active PilC protein was dissolved and purified by means of nickel chelate affinity chromatography. For this purpose, a nickel-NTA (Ni-nitrilo triacidic acid)-agarose column containing 300 μl column volumes was prepared, washed with 5 volumes double-distilled water and 10 ml of the supernatant was applied with the extracted PilC protein. By washing the column with 300 μl 50 mM TRIS.Cl, 50 mM imidazole, 10% glycerin, pH 8.0 proteins unspecifically bound to the nickel-NTA-agarose column were removed. After washing the column with 5-10 volumes 20 mM Na_(x)H_(x)PO₄, 150 mM NaCl, pH 7.5 (PBS), the biologically active PilC protein was eluted using a citrate/phosphate buffer (10 mM citric acid, 1 M Na_(x)H_(x)PO₄, pH 3.5, 10% glycerin, 0.15 M NaCl). The eluate was immediately neutralized using a 1 M Na₂HPO₄ solution. The PilC protein of this invention contained in the eluate in pure form is shock frozen in liquid nitrogen and stored at −70° C.

EXAMPLE 4

Detection of a Receptor for PilC on Human Epithelial Cells

Pili-coupled fluorescent MX Covashere particles (FMP) were produced as follows: FMPs (Duke Scientific Corporation, Paolo Alto, Calif., U.S.A.) have a surface consisting of active groups that makes a direct, spontaneous coupling of proteins possible. In general, 100 μl of the FMPs having a diameter of 0.5 μm were mixed with approx. 2 μg purified pili (according to Jonsson et al., 1991) in 100 μl PBS and mixed on a rotation disk for 2 hrs. at room temperature. The pili-coated particles were pelleted and washed in 1 ml blocking buffer (20 mM TRIS.Cl with 2% fetuine, pH 7.5), to block the free coupling groups. The protein concentration in the supernatant after the first centrifugation was compared to the used amount of pili to determine the yield achieved by the coupling. More than 80% of the used pili were covalently bound to FMPs in this reaction. The particles were again pelleted and resuspended in 100 μl PBS. The FMPs were coated with purified pili of an adherent Neisseria gonorrhoeae wild-type strains (FMP-pilin/PilC), as well as coated with purified pili of a pilC1/2 deletion mutant (MS11-N474: Facius et al., filed for publication) (FMP-pilin) and with fetuine (FMP-fetuine; negative control). For the detection of PilC-protein specific receptors on human epithelial cells, the attachment of the pili-coated FMPs to epithelial cell lines was examined. These experiments were carried out analogously with gonococci to the standard infection protocol. Epithelial cells were cultivated in 24-well cell culture plates on sterile cover glasses in RPMI medium with 5% fetal bovine serum (FCS) at 37° C. and under 5% CO₂ fumigation. Preconfluent epithelial cell monolayers were washed with fresh medium before 10 μl of the pili-loaded FMP suspension per well were added. The adherence lasted for 1 hr., during which the cultures were incubated at 37° C. and 5% CO₂. Then free FMPs were removed by 5 times washing with PBS and immobilized using 2% paraformaldehyde in PBS for 30 minutes. The preparations could finally be observed under a Zeiss fluorescence microscope. The results of this test as shown in Table 1 show that in contrast to the wild-type pili, the PilC-free pili mediate no attachment to epithelial cells. The attachment of PilC-free pili to epithelial cells, however, may be complemented by adding the biologically active PilC2 protein of this invention. The addition of 2 μg biologically active PilC2 protein in 100 μl PBS to 100 μl of the already coated FMP pilin was followed by incubation for 2 hrs. at 20° C. under constant mixing. The particles were pelleted, washed in 1 ml PBS and resuspended in 100 μl PBS. The FMP pilin additionally coated with PilC protein are called FMP (pilin+PilC).

TABLE 1 Attachment of fluorescent particles to human epithelial cells FMPs FMPs per epithelial cell FMP-Fetuine 0.1-3 FMP-Pilin/PilC 150-400 FMP-Pilin 0.1-5 FMP-(Pilin + PilC) 100-300

Attachment of fluorescent particles (FMPS) to human epithelial cells. FMP fetuine, fetuine-coupled FMPs; FMP-pilin/PilC, FMPs coupled with purified pili of the N. gonorrhoeae strain N137; FMP pilin, FMPs coupled with purified pili of the N. gonorrhoeae strains N474; FMP (pilin+PilC), FMPs coupled with purified pili of the N. gonorrhoeae strain N474 that were additionally incubated with the PilC protein of this invention (Example 4). The results of the attachment are stated in the average amount of FMPs per epithelial cell.

EXAMPLE 5

Direct Detection of the Attachment of PilC to Receptors on Human Epithelial Cells

For the detection of PilC-protein specific receptors on human epithelial cells, the attachment of the biologically active PilC protein of this invention to ME180 cells (human cervix carcinoma (ATCC HTB33)) was examined. The epithelial cells were cultivated at 37° C., 5% CO₂, in 4 Well Chamber Slides ™(Nunc) in RPMI medium using 5% fetal bovine serum (FCS). The addition of approx. 10 μg biologically active PilC protein at a maximal volume of 20 μl was followed by incubation for 30 minutes at 37° C. and 5% CO₂. Every well was washed three times with 1 ml PBS, then epithelial cells and bound PilC protein were immobilized for 30 minutes in 2% paraformaldehyde in PBS. To make bound PilC protein visible, immune fluorescence dyeing using specific anti serums against the biologically active PilC protein of this invention was carried out. These anti serums were obtained by means of immunization of Balb/c mice using the biologically active PilC protein of this invention. The fixated preparations were washed twice using 1 ml PBS and incubated with a dilution of 1:300 of the anti serums in PBS for 1 hr. The result was washed five times with PBS, 0.05% Tween20 in order to remove unspecifically bound antibodies (AK). To make the PilC AK complex visible, incubation was carried out for 60 minutes at 20° C. using a second AK directed against murine immuno globuline and marked with the fluorescent dye FITC, in a dilution of 1:2000 in PBS with 0.025% Tween20. Again, the resulting substance was thoroughly washed (5 times) with PBS, 0.05% Tween20, before the preparations were covered and analysed using a Zeiss fluorescence microscope. For negative control served (a) epithelial cells without PilC with second AK; (b) epithelial cells without PilC with first AK and second AK, and (c) epithelial cells with PilC and second AK. While the epithelial cells preincubated with the biologically active PilC protein of this invention were highly fluorescent after dyeing with specific PilC anti serums, they were only slightly fluorescent in all other monitoring experiments. For the purpose of further monitoring, the experiment was carried out with MDCK cells to which piliated Neisseria do not attach; correspondingly, no attachment of the PilC protein of this invention could be detected.

EXAMPLE 6

Competition of the Infection of Human Epithelial Cells with Neisseria

Carrying out the in vitro infection and/or inhibition experiments takes place with preconfluent ME180-cells [human cervix carcinoma (ATCC HTB33)] that were cultivated on cover glasses in a 24 well cell culture plate. For the inhibition of the pilus-mediated adherence of N. gonorrhoeae and N. meningitidis the cells were incubated for 30 minutes at 37° C. and 5% CO₂ in 500 μl RPMI medium, 5% FCS by addition of 20 μg of the biologically active PilC protein. For infection the bacteria were incubated overnight at 37° C., 5% CO₂ on a GC plate and then resuspended in 1 ml RPMI Medium, 5% FCS using a cotton swab. The determination of the bacteria density is carried out using the spectro-photometer. The approximately 2×10⁵ preconfluent epithelial cells were infected with 7×10⁷ bacteria and incubated for 1 hr. at 37° C., 5% CO₂. Stopping the infection takes place by washing five times with preheated PBS followed by fixing the cells with 2% paraformaldehyde in PBS. The fixed cells were then dyed for at least 15 minutes at room temperature using crystal violet (0.07% w/v) and the adherent bacteria were determined per ME 180. As can be seen in Table 2, all tested piliated Neisseria strains adhered when the biologically active PilC2 protein was not present, whereas the non-piliated N. gonorrhoeae strain did not adhere. In the presence of the biologically active PilC2 protein the attachment of the tested piliated Neisseria strains was reduced to background level. Thus, the reduction of the attachment to epithelial cells takes place independent of the variant of the PilC protein naturally formed by the bacteria (PilC1 in TRN289, compared to PilC2 in TRN290, compared to an unknown PilC protein in N. meningitidis N530). This serves to (i) prove that the PilC protein is an important bacterial adhesin (i.e. it is essential for the occurrence of an infection), (ii) confirm the low variability of different PilC proteins regarding the recognition of cellular receptors and thus (iii) prove the suitability of the inhibitors of this invention for inhibiting the interaction between the PilC protein and its cellular receptors.

TABLE 2 Competition of the attachment of Neisseria to human epithelial cells Neisseria per epithelial cell Pretreatment of the epithelial cells Neisseria strains without PilC 20 μg/ml PilC N137 165 — N174 — — TRN289 (pilE_(N137); PilC1) 140 — TRN290 (pilE_(N137); PilC2) 155 — N530 103 —

Competition of the attachment of pathogenic Neisseria to human epithelial cells. N137, piliated N. gonorrhoeae MS11 strain; N174, non-piliated strain derived from N. gonorrhoeae MS11 in which the pilE gene is deleted; TRN289, piliated N. gonorrhoeae MS11 strain that forms exclusively PilC1; TRN290, piliated N. gonorrhoeae MS11 strain that forms exclusively PilC2, and N530, N. meningitidis strain that forms an unknown PilC protein. The pretreatment of the epithelial cells with 20 μg/ml PilC2 protein of this invention is described in Example 6. The results of the competition experiment are stated in the average number of adherent bacteria per epithelial cell.

EXAMPLE 7

Identification of Other PilC-protein Encoding DNA Sequences

For the determination of the DNA sequence of the pilC2 genes, the BamHI/EcoRI fragment of the pTR27 was cloned into the bluescript SK vector (pTR34). With the exonuclease III suitable, overlapping deletion clones of pTR34 were produced and sequenced. The comparison of the DNA sequences coding for the PilC1 (A. Jonsson, Umea University, New Series No. 322, Department of Microbiology; ISSN 0346-6612) and those coding for the PilC2 protein (FIG. 4) using the computer program PCGENE/ALGIN showed 84% identity. The regions of identical sequences distribute island-like over both genes with a clear concentration at the 3′ terminal. With the aim to identify more sequences coding for PilC proteins, oligo nucleotide probes for the sequences identical between PilC1 and PilC2 were constructed. In the construct of the oligo nucleotide probes, particular care was taken to take turns in deriving the oligo nucleotides from the DNA (+) and (−) strands in order to be able to amplify corresponding fragments by means of PCR when necessary. This way, the entire DNA sequence of the pilC1 and pilC2 genes was divided up into overlapping fragments of approx. 400-500 bp. Besides, to every (+) strand oligo nucleotide the “M13mp” primer hybridization sequence was added at the 5′ terminal, to every (−) strand oligo nucleotide the “M13mp reverse” primer (Vieira and Messing, Gene 19, 259-268, 1982) hybridization sequence was added at the 5′ terminal to be able to directly identify the DNA sequence of the PCR fragment.

A selection of oligo nucleotide probes was marked with Biotin according to the regulations of the DIG oligo nucleotides tailing kit (Boehringer Mannheim) and used for hybridization against chromosomal DNA of N. gonorrhoeae digested with ClaI and PvuII. Southern Blot using the above-mentioned oligo nucleotide probes (Table 3) unambiguously indicated the existence of more pilC genes (besides pilC1 and pilC2) in the N. gonorrhoeae strain MS11 and in the N. meningitidis strain A1493. Furthermore, genes for PilC-analogous proteins were detected in a Pseudomonas aeruginosa strain using these probes. The such identified genes can now be cloned, characterized and further processed using standard techniques. This experiment proved that the described method is suitable for the identification of previously unknown genes for PilC and/or PilC analogous proteins.

TABLE 3 Oligo nucleotide probes for the identification of further PilC-protein encoding nucleotide sequences (SEQ. ID. NOS: 13-32) Oligo nucleo- 5′Position +/−DNA tide pilC1/pilC2 Sequence strand TR47 117/117 TATTATCATGAACGAGCG + TR48 392/413 CGGGTGGTACGAATCCAA − TR49 322/343 AAGGTTTCCGGTTTTGATG + TR50 692/713 ACGATGGTTTGATTATTA − TR51 590/611 GCGTATCTTTCAATTTGG + TR52 1033/1060 ACCACAGCGCGGGGGCGGTCAG − TR53 935/965 AGTCAAAGCAGGCCGCTG + TR54 1411/1423 CCGTCCAAGGCAGCAGCAC − TR55 1327/1339 AAAAACGACACTTTCGGC + TR56 1757/1799 TCCACGCCGTAGCGGTCG − TR57 1630/1672 AATCTGAAGCTCAGCTAC + TR58 2015/2072 AGGAAGGCGGCGTATTTG − TR59 1957/2016 TACACCGTCGGTACGCCGC + TR60 2329/2386 CTGCCAGTCGGGAAACGGC − TR61 2253/2311 TAGTAAATGGTCTGCAAAG + TR62 2611/2674 TACGCAATACCACGGTCG − TR63 2563/2626 TTGAGGGAAGGAGAACGCG + TR64 2878/2941 CCAG(G/A)TAACGCACATTAACC − TR65 2823/2886 AACCGTCTGCCCGAACGG + TR66 TTCGGACGGCATTTGCGG −

Examples of oligo nucleotide probes for the identification of further PilC-protein encoding nucleotide sequences. Examples TR47-TR65 were taken from the sequence comparison of the N. gonorrhoeae genes pilC1 and pilC2 in FIG. 4A. TR66 corresponds to a sequence region downstream of the coding region of the pilC gene. The position numbers refer to the pilC1 and/or pilC2 genes in FIG. 4A.

40 3270 base pairs nucleic acid Not Relevant Not Relevant DNA (genomic) NO NO Neisseria gonorrheae - 1..3270 /note= “PilC2” 1 GATCCTGCCG CCCCGAAGGG CGGGGGGTTT GACCGAAAAG GAAATACGAT GAATAAAACT 60 TTAAAAAGGC GGGTTTTCCG CCATACCGCG CTTTATGCCG CCATCTTGAT GTTTTCCCAT 120 ACCGGCGGGG GGGGGGGGGC GCAGGCGCAA ACCCGTAAAT ACGCTATTAT CATGAACGAG 180 CGAAAGCAGC CCGAGGTAAA GTGGGAGGGT CAATATAGTC AATCAACATT AAAGGACAAA 240 GGCAGGGAGC GGACATTTAG CCATACGAGC CAGAGAAACT GGAACGGCCA ACAAAACAAT 300 TTTATCTCAT TCAACAATAG CGATGAGCTT GTTTCCCGAC AAAGCGGTAC TGCCGTTTTT 360 GGCACAGCCA CCTACCTGCC GCCCTACGGC AAGGTTTCCG GTTTTGATGC CGACGGGCTG 420 AAAAAGCGCG GCAATGCCGT GAATTGGATT CGTACCACCC GGCCCGGGCT GGCAGGCTAC 480 ATCTACACCG GCGTCATATG CAGAGACACA GGGCAATGCC CCGAACTTGT CTATGAGACC 540 AAATTTTCCT TCGACGGCAT CGATTTGGCA AAAGGGGGAA ACCGAAAGCT GGATAGGCAC 600 CCGGACCCAA GCCGCGAAAA TTTGCCCATT TACAAATTGA AGGATCATCC ATGGTTGGGC 660 GTATCTTTCA ATTTGGGCGG CGAGGGTACC GCCAAAGATG GCAGATCATC CAGCAGATGG 720 ATATCTTCTT TTAGTGAAGA CAATAATAAT CAAACCATCG TCTTTACGAC ACGAGGCCAC 780 CCTATTTCCC TTGGCGACTG GCAGCGCGAA AGTACCGCCA TGGCCTATTA TCTGGACGCC 840 AAACTGCACC TGCTGGATAA AACACAGATT GAAAATATCG CGCCAGGCAA AACAGTGAAT 900 TTGGGCATCT TGAGACCGCG CGTCGAGGCA AAGGTAAGGC GGAAGTGGGA TCTGCTAAAT 960 TTTTGGGCTA AGTGGGACAT TAAAGATACC GGGCAGATTC CGGTCAAGCT CGGCCTGCCG 1020 GAAGTCAAAG CAGGCCGCTG CATCAACAAA CCGAACCCCA ATCCCAAATC AGCCCTTTCG 1080 CCGGCACTGA CCGCCCCCGC GCTGTGGTTC GGCCCTGTGC AAAATGGCAA GGTGCAGATG 1140 TATTCCGCTT CGGTTTCCAC CTACCCCGGC AGCTCGAGCA GCCGCATCTT CCTCCAAGAG 1200 CTGAAAACTA AAACCGACCC CGCCCGGCCC GGCCGGCATT CCCTCGCCGC TTTGAATGCG 1260 CAGGATATCA AATCCCGCGA GCCGAATTTC AACTCAAGGC AGACCGTCAT CCGATTGCCG 1320 GGCGGCGTGT ACCAGATCGC CCCGGGCAAT AGCGGCCGGG TCGCGGGTTT TAATGGCAAT 1380 GACGGCAAAA ACGACACTTT CGGCATCTAC AAGGACAGGC TCGTCACACC TGAGGTCGGC 1440 GAGTGGAGCG AAGTGCTGCT GCCTTGGACG GCCCGGTATT ACGGTAATGA CGATATATTT 1500 AAAACATTCA ACCAACCAAA CAGCAAAACA CAAAACGGCA AAAAACAATA CAGCCAAAAA 1560 TACCGCATCC GCACAAAAGA AAATGACAAT GACAAACCCC GCGATTTGGG CGACATCGTC 1620 AACAGCCCGA TTGTCGCGGT CGGCGGGTAT CTGGCAACTT CTGCCAACGA CGGGATGGTG 1680 CATATCTTCA AAAAAACCGG CACGGATGAA CGCAGCTACA ATCTGAAGCT CAGCTACATC 1740 CCCGGTACGA TGGAGCGTAA GGATATTGAA GGCAATGACT CCGACCTCGC CAAAGAGCTG 1800 CGCACCTTTG CCGAAAAAGG CTATGTGGGC GACCGCTACG GCGTGGACGG CGGCTTTGTC 1860 TTGCGCCGCA TTACAGATGA CCAAGACAAG CAAAAACATT TCTTTATGTT TGGTGCGATG 1920 GGCCTGGGCG GCAGAGGCGC GTATGCCTTG GATTTAAGCA AAATCGACAG CAGCAACCTG 1980 ACCGGCGTTT CCATGTTTGA TGTCCAAAAC GACAAAAATA ACAATAACAA TAAGAATGAC 2040 AATAATCGCG TGAAATTAGG CTACACCGTC GGTACGCCGC AAATCGGCAA AACCCAAAAC 2100 GGCAAATACG CCGCCTTCCT CGCTTCCGGT TATGCGGCTA AAAATATTGG CAGCGGCGAT 2160 AATACAACCG CGCTGTATGT GTATGATTTG GAAAACACCA GTGGTAGTCT GATTAAAAAA 2220 ATCGAAGCAC CCGGCGGCAA AGGCGGGCTT TCGTCCCCCA CGCTGGTGGA TAAAGATTTG 2280 GACGGCACGG TCGATATCGC CTATGCCGGC GACCGGGGCG GCAATATGTA CCGCTTTGAT 2340 TTGAGCAATT CCGATTCTAG TAAATGGTCT GCAAAGGTTA TTTTCGAAGG CGACAAGCCG 2400 ATTACCTCCG CGCCCGCCGT TTCCCGACTG GCAGACAAAC GCGTGGTTAT CTTCGGCACG 2460 GGCAGCGATT TGAGTGAACA GGATGTACTG GATACGGACA AACAATATAT TTACGGTATC 2520 TTTGACGACG ATAAGTCGAC GGTTAATGTA AAGGTAACAA ACGGCACGGG AGGCGGGCTG 2580 CTCGAGCAAG TGCTTAAAGA GGAAAGTAAA ACCTTATTCC TGAGCAATAA TAAGGCATCC 2640 GGCGGATCGG CCGATAAAGG GTGGGTAGTG AAATTGAGGG AAGGAGAACG CGTTACCGTC 2700 AAACCGACCG TGGTATTGCG TACCGCCTTT GTCACCATCC GCAAATATAC GGATACGGAC 2760 AAATGTGGCG CGCAAACCGC CATTTTGGGC ATCAATACCG CCGACGGCGG CGCATTGACT 2820 CCGAGAAGCG CGCGCCCGAT TGTGCCGGAT CACAATTCGG TTGCGCAATA TTCCGGCCAT 2880 CAGAAAATGA ACGGCAAGTC CATCCCCATA GGCTGCATGT GGAAAAACAG CAAAACCGTC 2940 TGCCCGAACG GATATGTTTA CGACAAACCG GTTAATGTGC GTTACCTGGA CGAAAAGAAA 3000 ACAGACGATT TCCCCGTCAC GGCAGACGGT GATGCAGGCG GCAGCGGAAC ATTCAAAGAG 3060 GGTAAAAAAC CCGCCCGCAA TAACCGGTGC TTCTCCGGAA AAGGTGTGCG CACCCTGCTG 3120 ATGAACGATT TGGACAGCTT GGATATTACC GGCCCGATGT GCGGTATCAA ACGCTTAAGC 3180 TGGCGCGAAG TCTTCTTCTG ACCCGCCTGC GCGGCCGGTT TTTCCGCAAA TCCCGTCCGA 3240 AAGGTCTTCG GACGGCATTT TTTTGCGTTT 3270 3114 base pairs nucleic acid Not Relevant Not Relevant DNA (genomic) NO Neisseria meningitidis - 1..3114 /note= “PilC A1493” 2 ATGAATAAAA CTTTAAAAAG GCAGGTTTTC CGCCATACCG CGCTTTATGC CGCCATCTTG 60 ATGTTTTCCC ATACCGGCGG GGGGGGGGCG ATGGCGCAAA CCCATAAATA CGCTATTATC 120 ATGAACGAGC GAAACCAGCT CGAGGTAAAG GGGAATGGGC AATATTCAAC AATAAAGGAC 180 AAAGACAGGG AACGCAAATT TATCTATAAT AAAGACAGAG GGGGTGGAGG CTCTGTCTTT 240 TTCGACAATA CCGATACCCT TGTTTCCCAA CAAAGAGGTA CTGCCGTTTT TGGCACAGCC 300 ACCTACCTGC CGCCCTACGG CAAGGTTTCC GGTTTTGATG CCGACGGGCT GCAAAAGCGC 360 AACAATGCCG TCGATTGGAT TCATACCACC CAGGCCGGGC TGGCAGGCTA CGCCTACACC 420 GACGTCATAT GCAGAAGCAA CCAATGCCCC CAACTTGTCT ATGAGACCAA ATTTTCCTTC 480 GACGGCATCG GTTTGGCAAA AAATGCGGGC AGCCTGGATA GGCACCCGGA CCCAAGCCGC 540 GAAAATTCGC CCATTTACAA ATTGAAAGAT CATCCATGGT TGGGCGTATC TTTCAATTTG 600 GGCAGCGAGA ATACCGTCAA AGATGGCAAA TCATTCAACA AATTGATATC TTCTTTTAGT 660 GAAGGCAATA ATAATCAAAC CATCGTCTCT ACGACACGAG GCCACTCTAT TTCCCTTAGC 720 GACTGGAAGC GCGAACATAC CGCCATGGCC TATTATCTGA ACGCCAAACT GCACCTGCTG 780 GACAAAAAAG GGATTGAAGA TATCGCCCAA GGCAAAACAG TGGATTTGGG CACCTTGAGA 840 CCGCGCGTCG AGGCAACGGT AAGGCGGGGG GAGCTGCTAA ATTTTTGGGC TACGTGGAAG 900 ATTGAAGATA AAGGGAACAT TACAGTCCGC CTCGGCCTGC CGGAAGTCAA AGCAGGCCGC 960 TGCGTCAACA AAGCGAACCC CAATCCCAAC GCCAAAGCCC CCTCCCCCGC ACTGACCGCC 1020 CCCGCGCTGT GGTTCGGACC TGTGAAAGAT GGTAAGGCGG AGATGTATTC CGCTTCGGTT 1080 TCTACCTACC CCGACAGTTC GAGCAGCCGC ATCTACCTTC AAAATCTGAA AAGAAAAACC 1140 GACCCCGGCA AACCCGGCCG CCATTCCCTC GAAACCTTGA CTGAGAATGA TATTAAAAGT 1200 CGAGAGCCGA ATTTCACAGG GCGGCAAACC ATCATCCGAT TGAATGGCGG CGTACGTGAG 1260 ATCAAACTGG ATAGAAACAA TACTGAGGTC GTCAATTTTA ATGGAAATGA CGGCAACAAC 1320 GACACTTTCG GCATTGTTAA GGACTTGGGC GTCGAACCTG ATACCAGCGA GTGGAAAAAA 1380 GTATTGCTGC CTTGGACGGT TCGGGGTTTT GCTGATGACA ATAAATTTAA AGCATTCAAC 1440 AAAGAAGAAA ACAACGACAA CAAGCCAAAA TACAGCCAAA AATACCGCAG CCGCGACAAC 1500 AACAAGGGCG AACGCAATTT GGGCGACATC GTCAACAGCC CCATCGTGGC GGTCGGCGAG 1560 TATTTGGCTA CTTCCGCCAA CGACGGGATG GTGCATATCT TCAAACAAAG CGGCGGGGAC 1620 AAGCGCAGCT ACAATCTGAA GCTCAGCTAC ATCCCTGGAA CGATGCCGCG CAAGGATATT 1680 CAAAACACCG AATCCACCCT TGCCAAAGAC GTGCGCACCT TTGCCGAAAA AGGCTATGTG 1740 GGCGACCGCT ACGGCGTGGA CGGCGGCTTT GTCTTGCGCA AAGTTGATAA CTTAAACGGG 1800 CAAAACCGCG TGTTTATGTT CGGCGCGATG GGCTTTGGCG GCAGAGGCGC GTATGCCTTG 1860 GATTTGACCA AAGCCGACGG CAGTGACCCG ACCGCCGTTT CCCTGTTTGA TGTAAAAGAT 1920 AACGGCAATA ATGGCAATAA TCGCGTGGAA TTAGGCTACA CCGTCGGCAC GCCGCAAATC 1980 GGCAAAACCC ACGACGGCAA ATACGCCGCC TTCCTCGCCT CCGGTTATGC GACTAAAGAA 2040 ATTATTACCA GCGGCGACAA TAAAACCGCG CTGTATGTGT ATGATTTGGA AGGAAACGGT 2100 ACGAATAATC TGATTAAAAA AATCGAAGTA CCCGGCGGCA AGGGCGGGCT TTCGTCCCCC 2160 ACGCTGGTGG ATAAAGATTT GGACGGCACG GTCGATATCG CCTATGCCGG CGATCGCGGC 2220 GGGAATATGT ACCGCTTTGA TTTGAGCAGT CAAGATCCTC AACAATGGTC TGTACGCACT 2280 ATTTTTGAAG GCACAAAACC GATTACTTCC GCGCCCGCTA TTTCCCAACT GAAAGACAAA 2340 CGCGTGGTCA TCTTCGGCAC GGGCAGCGAT TTGAGTGAAG AGGATGTGGA CAATATGGAA 2400 GAACAATATA TTTACGGTAT CTTCGACGAC GATACGGCGA CGACGGGTAC TGTAAACTTC 2460 AGCGATTCGG GAGGCGGGCT GCTTGAGCAA GTGCTTCGTA GGGATAACGA CAATAAAACC 2520 TTATTCCTGA CCGATTACAA GCGATCCGAC GGATCGGGCA ATAAGGGCTG GGTAGTGAAA 2580 TTGAAGGACG GACAGCGCGT TACCGTCAAA CCGACCGTGG TATTGCGTAC CGCCTTTGTA 2640 ACCATCCATA AATATACGGG TACGGACAAA TGCGGCGCGG AAACCGCCAT TTTGGGCATC 2700 AATACCGCCG ACGGCGGCAA GCTGACCAAG AAAAGCGCGC GCCCGATTGT GCCGGAAGCC 2760 AATACGGCTG TCGCGCAATA TTCCGGCCAT AAGAAAGGCA CCAACGGCAA ATCCATCCCT 2820 ATAGGTTGTA TGCAAAAAAG CAATGAAATC GTCTGCCCGA ACGGATATGT TTACGACAAA 2880 CCGGTTAATG TGCGTTATCT GGATGAAAAG AAAACAGACG GATTTTCAAC AACGGCAGAC 2940 GGCGATGCGG GCGGCAGCGG TATAGACCCC GCCGGCAAGC GTTCCGGCAA AAACAACCGC 3000 TGCTTCTCCC AAAAAGGGGT GCGCACCCTG CTGATGAACG ATTTGGACAG CTTGGACATT 3060 ACCGGCCCGA CGTGCGGTAT GAAACGAATC AGCTGGCGTG AAGTCTTCTA CTGA 3114 3567 base pairs nucleic acid Not Relevant Not Relevant DNA (genomic) NO Neisseria gonorrheae - 1..3567 /note= “PilC1 gene” 3 GATCCGCCCG GTGCTTGGGC GCCTTAGGGA ACCGTTCCCT TTGAGCCGGG GCGGGGCAAC 60 GCCGTACCGG TTTTTGTTAA TCCGCTATAA AAGGCGGGCT ATAGGGTAGG CTTCATCCTG 120 CCAATCTCAC TGAATCCGTC AATTTCCGCA ATTCAATTAA ATACCGTCAA ACCGATGCCG 180 TCATTCCGCG CAGGCGGGAA TCCGGACCGG TCGGGCATCT GCGGCGGTTT GCTAAAAAAC 240 GCTTTACCGT GATAAGTGCG CAAAGTTAAA ATGGGGAGGT AAGCTTTTCA ATCAGCAATC 300 CGGCGGGCGC GGAATCGGGC GGTTTACCGA ACCCCGGCGT TCGCGGCGCC CGTCCCGCGA 360 AGGCAAACTT AAGGAATAAA ATATGAATAA AACTTTGAAA CGGCAGGTTT TCCGCCATAC 420 CGCGCTTTAT GCCGCCATCT TGATGTTTTC CCATACCGGC GGGGGGGGGG GGCGATGGCG 480 CAAACCCATC AATACGCTAT TATCATGAAC GAGCGAAACC AGCCCGAGGT AAAGCAGAAT 540 GTGCCATCTT CAATAAAGGA CAAAGACAGG AGGCGCGAAT ATACTTATTA TACGCACAGA 600 ACAGGAGCAG GCTCTGTCTC ATTCAACAAT AACGATACCC TTGTTTCCCA ACAAAGCGGT 660 ACTGCCGTTT TTGGCACAGC CACCTACCTG CCGCCCTACG GCAAGGTTTC CGGTTTTGAT 720 GCCGTCGCTC TGAAAGAGCG CAACAATGCC GTTGATTGGA TTCGTACCAC CCGCATCGCG 780 CTGGCAGGCT ACTCCTACAT CGACGTCATA TGCAGAAGCT ACACAGGCTG TCCCAAACTT 840 GTCTATAAAA CCCGATTTAC CTTCGGTCAA CAAGGGTTGA AAAGAAAGGC AGGCAGCAAG 900 CTGGATATAT ACGAAGACAA AAGCCGCGAA AATTCGCCCA TTTACAAATT GTCGGATTAT 960 CCTTGGTTGG GCGTATCTTT CAATTTGGGC AGCGAGAATA CCGTCCAAAA TAGCAAATTA 1020 TTCAACAAAT TGATATCTTC TTTTAGAGAA GGCAATAATA ATCAAACCAT CGTCTCTACG 1080 ACAGAAGGCA ACCCTATTTC CCTTGGCGAC CGGCAGCGCG AACATACCGC CGTGGCCTAT 1140 TATCTGAACG CCAAACTGCA CCTGCTGGAC AAAAAAGGGA TTGAAGATAT CGCCCAAGGC 1200 AAAATAGTGG ATTTGGGTAT CTTGAAACCG CACGTCGAGA CGACAGGACG AAGCTTGCTA 1260 GATTTTTGGG CTAGGTGGGA CATTAAAGAT ACCGGGCAGA TTCCGGTCAA GCTCGGCCTG 1320 CCGCAAGTCA AAGCAGGCCG CTGCACCAAC AAACCGAACC CCAATAATAA TACCAAAGCC 1380 CCTTCGCCGG CACTGACCGC CCCCGCGCTG TGGTTCGGAC CCGGGCAAGA TGGTAAGGCG 1440 GAGATGTATT CCGCTTCGGT TTCCACCTAC CCCGACAGTT CGAGCAGCCG CATCTTCCTC 1500 CAAGAGCTGA AAACTCAAAC CGAACCCGGC AAACCCGGCC GCTATTCCCT CAAATCTTTG 1560 AATGATGGTG AGATTAAAAG TCGACAGCCG AGTTTCAACG GGCGGCAAAC AATCATCCGA 1620 TTGGATGACG GCGTACATTT GATCAAACTG AATGGAAGCA AGGATGAGGT CGCCGCTTTT 1680 GTCAATTTAA ATGGAAACAA CACCGGCAAA AACGACACTT TCGGCATTGT TAAGGAAGCG 1740 AACGTCAATC TTGACGCCGA CGAGTGGAAA AAAGTGCTGC TGCCTTGGAC GGTTCGGGGT 1800 CCCGATAATG ACAATAAATT TAAATCAATT AACCAAAAAC CAGAAAAATA CAGCCAAAGA 1860 TACCGCATCC GCGACAACAA CGGCAATCGC GATTTGGGCG ACATCGTCAA CAGCCCGATT 1920 GTCGCGGTCG GCGGGTATTT GGCAACCGCC GCGAACGACG GGATGGTGCA TATCTTCAAA 1980 AAAAACGGCG GCAGTGATGA ACGCAGCTAC AATCTGAAGC TCAGCTACAT CCCCGGCACG 2040 ATGCCGCGCA AGGATATTCA AAGCCAAGAA TCCACCCTTG CCAAAGAGCT GCGCGCCTTT 2100 GCCGAAAAAG GCTATGTGGG CGACCGCTAC GGCGTGGACG GCGGCTTTGT CTTGCGCCAA 2160 GTCGAACTGA GCGGGCAAAA ACACGTGTTT ATGTTCGGCG CGATGGGTTT TGGCGGCAGG 2220 GGCGCGTATG CCTTGGATTT AAGCAAAATC AACGGAAATT ATCCGGCCGC CGCCCCCCTG 2280 TTTGATGTCA AAGATGGCGA TAATAACGGC AAAAATCGCG TGAAAGTGGA ATTAGGCTAC 2340 ACCGTCGGTA CGCCGCAAAT CGGCAAAATC CGCAACGGCA AATACGCCGC CTTCCTCGCC 2400 TCCGGTTATG CGGCTAAAAA AATTGACGAC TCAACAAATA AAACCGCGCT GTATGTATAT 2460 GATTTGAAAG ACACCTTAGG TACGCCGATT GCAAAAATCG AAGTGAAGGA CGGCAAAGGC 2520 GGGCTTTCGT CCCCCACGCT GGTGGATAAA GATTTGGACG GCACGGTCGA TATCGCCTAT 2580 GCCGGCGACC GGGGCGGCAA TATGTACCGC TTTGATTTGA GCAATTCCGA TTCTAGTAAA 2640 TGGTCTGCAA AGGTTATTTT CGAAGGCGAC AAGCCGATTA CCTCCGCGCC CGCCGTTTCC 2700 CGACTGGCAG ACAAACGCGT CGTCATCTTC GGTACGGGCA GCGATTTGAC CGAAGATGAT 2760 GTACTGAATA CGGGCGAACA ATATATTTAC GGTATCTTTG ACGACGATAA GGGGACGGTT 2820 AAGGTAACGG TACAAAACGG CACGGCAGGC GGGCTGCTCG AGCAACACCT TACTCAGGAA 2880 AATAAAACAT TATTCCTGAA CAAGAGATCC GACGGTTCGG GCAGCAAGGG CTGGGCGGTG 2940 AAATTGAGGG AAGGAGAACG CGTTACCGTC AAACCGACCG TGGTATTGCG TACCGCCTTC 3000 GTAACCATCC GCAAATATAA CGACGGCGGC TGCGGCGCGG AAACCGCCAT TTTGGGCATC 3060 AATACCGCCG ACGGCGGCGC ATTGACTCCG AGAAGCGCGC GCCCGATTGT GCCGGATCAC 3120 AATTCGGTTG CGCAATATTC CGGCCATAAG ACAACCTCCA AAGGCAAATC CATCCCTATA 3180 GGTTGTATGG ACAAAGACGG TAAAACCGTC TGCCCGAACG GATATGTTTA CGACAAGCCG 3240 GTTAATGTGC GTTATCTGGA TGAAACGGAA ACAGACGGAT TTTCAACGAC GGCGGACGGC 3300 GATGCGGGCG GCAGCGGTAT AGACCCCGCC GGCAGGCGTC CCGGCAAAAA CAACCGCTGC 3360 TTCTCCAAAA AAGGGGTGCG CACCCTGCTG ATGAACGATT TGGACAGCTT GGATATTACC 3420 GGCCCGATGT GCGGTATCAA ACGCTTAAGC TGGCGCGAAG TCTTCTTCTG ACCGGCCTGC 3480 GCGGCCGGTT TTTCCGCAAA TGCCGTCCGA AAGGCCTTCG GACGGCATTT TTTTGCGTTT 3540 TTCGGGAGGG GGGCGGCAAA TGAAACG 3567 13 base pairs nucleic acid Not Relevant Not Relevant DNA (genomic) NO not provided misc_feature 1..13 /note= “example homopolymeric basis for ”invariable heteropolymeric nucleotide sequence“” 4 GGGGGGGGGG GGG 13 20 base pairs nucleic acid single linear other nucleic acid /desc = “oligonucleotide probe CG31” NO not provided 5 CGATGGCGCA AACCCATCAA 20 20 base pairs nucleic acid single linear other nucleic acid /desc = “oligonucleotide probe CG32” not provided 6 CGCAGGCGCA AACCCGTAAA 20 32 base pairs nucleic acid single linear other nucleic acid /desc = “PCR primer TR12” not provided 7 TTGGATCCGA CGTCCGAAAA GGAAATACGA TG 32 30 base pairs nucleic acid single linear other nucleic acid /desc = “PCR primer TR28” not provided 8 GCTCCACCAC CTCCGCCGGT ATGGGAAAAC 30 36 base pairs nucleic acid single linear other nucleic acid /desc = “PCR primer TR27” not provided 9 ACCGGCGGAG GTGGTGGAGC GCAGGCGCAA ACCCGT 36 19 base pairs nucleic acid single linear other nucleic acid /desc = “PCR primer TR23” not provided 10 TGTGTCTCTG CATATGACG 19 37 base pairs nucleic acid single linear other nucleic acid /desc = “PCR primer TR71” not provided 11 GTGATGATGG TGGTGATGGG TTTGCGCCTG CGCTCCA 37 36 base pairs nucleic acid single linear other nucleic acid /desc = “PCR primer TR70” not provided 12 CATCACCACC ATCATCACCG TAAATACGCT ATTATC 36 18 base pairs nucleic acid single linear other nucleic acid /desc = “PCR primer TR47” not provided 13 TATTATCATG AACGAGCG 18 18 base pairs nucleic acid single linear other nucleic acid /desc = “PCR primer TR48” not provided 14 CGGGTGGTAC GAATCCAA 18 19 base pairs nucleic acid single linear other nucleic acid /desc = “PCR primer TR49” not provided 15 AAGGTTTCCG GTTTTGATG 19 18 base pairs nucleic acid single linear other nucleic acid /desc = “PCR primer T50” not provided 16 ACGATGGTTT GATTATTA 18 18 base pairs nucleic acid single linear other nucleic acid /desc = “PCR primer TR51” not provided 17 GCGTATCTTT CAATTTGG 18 22 base pairs nucleic acid single linear other nucleic acid /desc = “PCR primer T52” not provided 18 ACCACAGCGC GGGGGCGGTC AG 22 18 base pairs nucleic acid single linear other nucleic acid /desc = “PCR primer T53” not provided 19 AGTCAAAGCA GGCCGCTG 18 19 base pairs nucleic acid single linear other nucleic acid /desc = “PCR primer T54” not provided 20 CCGTCCAAGG CAGCAGCAC 19 18 base pairs nucleic acid single linear other nucleic acid /desc = “PCR primer T55” not provided 21 AAAAACGACA CTTTCGGC 18 18 base pairs nucleic acid single linear other nucleic acid /desc = “PCR primer T56” not provided 22 TCCACGCCGT AGCGGTCG 18 18 base pairs nucleic acid single linear other nucleic acid /desc = “PCR primer T57” not provided 23 AATCTGAAGC TCAGCTAC 18 18 base pairs nucleic acid single linear other nucleic acid /desc = “PCR primer TR58” not provided 24 AGGAAGGCGG CGTATTTG 18 19 base pairs nucleic acid single linear other nucleic acid /desc = “PCR primer T59” not provided 25 TACACCGTCG GTACGCCGC 19 19 base pairs nucleic acid single linear other nucleic acid /desc = “PCR primer T60” not provided 26 CTGCCAGTCG GGAAACGGC 19 19 base pairs nucleic acid single linear other nucleic acid /desc = “PCR primer T61” not provided 27 TAGTAAATGG TCTGCAAAG 19 18 base pairs nucleic acid single linear other nucleic acid /desc = “PCR primer TR62” not provided 28 TACGCAATAC CACGGTCG 18 19 base pairs nucleic acid single linear other nucleic acid /desc = “PCR primer TR63” not provided 29 TTGAGGGAAG GAGAACGCG 19 20 base pairs nucleic acid single linear other nucleic acid /desc = “PCR primer TR64” not provided 30 CCAGRTAACG CACATTAACC 20 18 base pairs nucleic acid single linear other nucleic acid /desc = “PCR primer TR65” not provided 31 AACCGTCTGC CCGAACGG 18 18 base pairs nucleic acid single linear other nucleic acid /desc = “PCR primer T66” not provided 32 TTCGGACGGC ATTTGCGG 18 24 base pairs nucleic acid Not Relevant linear cDNA to mRNA NO NO not provided CDS 1..24 33 CAT ACC GGC GGG GGG GGG GGG GCG 24 His Thr Gly Gly Gly Gly Gly Ala 1 5 8 amino acids amino acid linear protein not provided 34 His Thr Gly Gly Gly Gly Gly Ala 1 5 24 base pairs nucleic acid Not Relevant linear cDNA to mRNA NO not provided CDS 1..24 35 CAT ACC GGT GGA GGT GGT GGA GCG 24 His Thr Gly Gly Gly Gly Gly Ala 10 15 8 amino acids amino acid linear protein not provided 36 His Thr Gly Gly Gly Gly Gly Ala 1 5 24 base pairs nucleic acid Not Relevant linear cDNA to mRNA NO not provided CDS 1..24 37 GCG CAG GCG CAA ACC CGT AAA TAC 24 Ala Gln Ala Gln Thr Arg Lys Tyr 10 15 8 amino acids amino acid linear protein not provided 38 Ala Gln Ala Gln Thr Arg Lys Tyr 1 5 24 base pairs nucleic acid Not Relevant linear cDNA to mRNA NO not provided CDS 1..24 39 ACC CAT CAC CAC CAT CAT CAC CGT 24 Thr His His His His His His Arg 10 15 8 amino acids amino acid linear protein not provided 40 Thr His His His His His His Arg 1 5 

What is claimed is:
 1. An isolated DNA molecule comprising i) a first DNA fragment that is a heteropolymeric nucleotide sequence that encodes a homopolymeric amino acid sequence or that encodes a signal peptide and lacks a homopolymeric nucleotide sequence; and ii) a second DNA fragment that is a nucleotide sequence that encodes a mature PilC protein having at least one biological activity selected from the group consisting of supporting assembly of a type 4 pilus, mediating attachment of type 4 pili to a cellular receptor for type 4 pili and being immunogenic for induction of antibodies that block the attachment of type 4 pili to a cellular receptor for type 4 pili; wherein said first DNA fragment is operatively-linked to the 5′ end of said second DNA fragment to prevent phase variation in the expression by a host cell of the protein encoded by said second DNA fragment.
 2. The isolated DNA molecule of claim 1 wherein said first DNA fragment is a heteropolymeric nucleotide sequence that encodes a homopolymeric amino acid sequence.
 3. The isolated DNA molecule of claim 2, wherein said homopolymeric amino acid sequence is poly-glycine.
 4. The isolated DNA molecule of claim 2, wherein said homopolymeric amino acid sequence is 3 to 5 amino acids long.
 5. The isolated DNA molecule of claim 1, wherein said second DNA fragment further comprises a nucleotide sequence that encodes a (histidine)₆ sequence.
 6. The isolated DNA molecule of claim 2, wherein said second DNA fragment further comprises a nucleotide sequence that encodes a (histidine)₆ sequence.
 7. The isolated DNA molecule of claim 5, wherein said nucleotide sequence encoding a (histidine)₆ sequence is attached at the 5′- or at the 3′-end of the nucleotide sequence encoding the mature PilC protein.
 8. The isolated DNA molecule of claim 1, wherein said second DNA fragment comprises a nucleotide sequence selected from the group consisting of SEQ. ID. NOS. 1 to
 32. 9. The isolated DNA molecule of claim 8, wherein said second DNA fragment comprises a nucleotide sequence selected from the group consisting of SEQ. ID. NOS. 1 to
 3. 10. The isolated DNA molecule of claim 1, wherein said second DNA fragment comprises a nucleotide sequence that is obtained by amplifying a template DNA using a pair of primers, one member of said pair being selected from the group consisting of SEQ. ID. NO. 13, SEQ. ID. NO. 15, SEQ. ID. NO. 17, SEQ. ID. NO. 19, SEQ. ID. NO. 21, SEQ. ID. NO. 23, SEQ. ID. NO. 25, SEQ. ID. NO. 27, SEQ. ID. NO. 29 and SEQ. ID. NO. 31; and the second member of said pair being selected from the group consisting of SEQ. ID. NO. 14, SEQ. ID. NO. 16, SEQ. ID. NO. 18, SEQ. ID. NO. 20, SEQ. ID. NO. 22, SEQ. ID. NO. 24, SEQ. ID. NO. 26, SEQ. ID. NO. 28, SEQ. ID. NO. 30 and SEQ. ID. NO.
 32. 11. The isolated DNA molecule of claim 2, wherein said second DNA fragment comprises a nucleotide sequence that is obtained by amplifying a template DNA using a pair of primers, one member of said pair being selected from the group consisting of SEQ. ID. NO. 13, SEQ. ID. NO. 15, SEQ. ID. NO. 17, SEQ. ID. NO. 19, SEQ. ID. NO. 21, SEQ. ID. NO. 23, SEQ. ID. NO. 25, SEQ. ID. NO. 27, SEQ. ID. NO. 29 and SEQ. ID. NO. 31; and the second member of said pair being selected from the group consisting of SEQ. ID. NO. 14, SEQ. ID. NO. 16, SEQ. ID. NO. 18, SEQ. ID. NO. 20, SEQ. ID. NO. 22, SEQ. ID. NO. 24, SEQ. ID. NO. 26, SEQ. ID. NO. 28, SEQ. ID. NO. 30 and SEQ. ID. NO.
 32. 12. The isolated DNA molecule of claim 11, wherein said second DNA fragment further comprises a nucleotide sequence that encodes a (histidine)₆ sequence.
 13. The isolated DNA molecule of claim 12, wherein said nucleotide sequence encoding a (histidine)₆ sequence is attached at the 5′- or at the 3′-end of the nucleotide sequence encoding the mature PilC protein.
 14. The isolated DNA of claim 11, wherein said template DNA is obtained from a bacterium of the genus Neisseria.
 15. A recombinant vector comprising the isolated DNA molecule of claim
 1. 16. A recombinant vector comprising the isolated DNA molecule of claim
 5. 17. A recombinant vector comprising the isolated DNA molecule of claim
 11. 18. A recombinant vector comprising the isolated DNA molecule of claim
 12. 19. The recombinant vector of claim 15, which further comprises a promoter that is functional in a Neisseria host cell that is operatively linked to said isolated DNA molecule so that said PilC protein is expressed by said host cell.
 20. The recombinant vector of claim 16, which further comprises a promoter that is functional in a Neisseria host cell that is operatively linked to said isolated DNA molecule so that said PilC protein is expressed by said host cell.
 21. The recombinant vector of claim 17, which further comprises a promoter that is functional in a Neisseria host cell that is operatively linked to said isolated DNA molecule so that said PilC protein is expressed by said host cell.
 22. The recombinant vector of claim 18, which further comprises a promoter that is functional in a Neisseria host cell that is operatively linked to said isolated DNA molecule so that said PilC protein is expressed by said host cell.
 23. A host cell transformed with the recombinant vector of claim
 15. 24. A host cell transformed with the recombinant vector of claim
 16. 25. A host cell transformed with the recombinant vector of claim
 17. 26. A host cell transformed with the recombinant vector of claim
 18. 27. A host cell transformed with the recombinant vector of claim
 19. 28. A host cell transformed with the recombinant vector of claim
 20. 29. A host cell transformed with the recombinant vector of claim
 21. 30. A host cell transformed with the recombinant vector of claim
 22. 31. A method for producing a PilC protein comprising culturing the host cell of claim 16 under conditions suitable for expression of said PilC protein and isolating the PilC so produced from the culture.
 32. A method for producing a PilC protein comprising culturing the host cell of claim 18 under conditions suitable for expression of said PilC protein and isolating the PilC so produced from the culture. 